Simple Interest
Math MCQs

Question :    If Barbara borrowed $3550 from a bank at a rate of 2% simple interest per annum then find the amount to be paid after 2 years.

Correct Answer  $3692

Solution & Explanation

Solution

Given,

Principal (P) = $3550

Rate of Simple Interest (SI) = 2%

Time (t) = 2 years

Thus, Amount (A) = ?

The Rate of Interest is always calculated per annum, i.e. per year.

Thus, here 2% simple interest means, Rate of Simple Interest (SI) is 2% per annum.

Method (1) Using Formula

Calculation of Simple Interest

Formula to Calculate Simple Interest

Simple Interest (SI) = Principal × Rate × Time

Thus, Simple Interest (SI) = $3550 × 2% × 2

= $3550 ײ/₁₀₀ × 2

= ^{3550 × 2 × 2}/₁₀₀

= ^{7100 × 2}/₁₀₀

= ¹⁴²⁰⁰/₁₀₀

= $142

Thus, Simple Interest = $142

Calculation of Amount

The total money paid to the lender by a borrower is called the Amount.

In other words, sum of priciple and interest is called the Amount.

Formula to Calculate the Amount

Amount = Principal + Interest

Thus, Amount = $3550 + $142

= $3692

Thus, Amount to be paid = $3692 Answer

Method (2)

Calculation of Amount when Principal, Rate of Simple Interest and Time are given

Calculation of Amount directly using Principal, SI, and Time

Formula to calculate the Amount

Amount (A) = Principal (P) + Principal(P) × Rate of Interest (SI) × Time (t)

⇒ A = P + PRT

Here in the question, P = $3550

Rate of Simple Interest (SI) or (R) = 2%

And, Time (t) = 2 years

Thus, Amount (A)

= $3550 + ($3550 × 2% × 2)

= $3550 + ($3550 ײ/₁₀₀ × 2)

= $3550 + (^{3550 × 2 × 2}/₁₀₀)

= $3550 + (^{7100 × 2}/₁₀₀)

= $3550 + (¹⁴²⁰⁰/₁₀₀)

= $3550 + $142 = $3692

Thus, Amount (A) to be paid = $3692 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 2%

This, means, $2 per $100 per year

∵ For $100, the simple interest in 1 year = $2

∴ For $1, the simple interest in 1 year = ²/₁₀₀

∴ For $3550, the simple interest in 1 year

= ²/₁₀₀ × 3550

= ^{2 × 3550}/₁₀₀

= ⁷¹⁰⁰/₁₀₀ = $71

Thus, simple interest in 1 year = $71

Therefore, simple interest for 2 years

= Simple interest for 1 year × 2

= $71 × 2 = $142

Thus, Simple Interest (SI) = $142

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3550 + $142

= $3692

Thus, Amount to be paid = $3692 Answer

Similar Questions

(1) Find the amount to be paid if William borrowed a sum of $5500 at 9% simple interest for 8 years.

(2) Calculate the amount due after 9 years if Susan borrowed a sum of $5650 at a rate of 10% simple interest.

(3) How much loan did Paul borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $8375 to clear it?

(4) If Sandra paid $5340 to settle his loan which he had taken 4 years before at a simple interest of 5%, then find the loan taken.

(5) Calculate the amount due after 9 years if Richard borrowed a sum of $5600 at a rate of 2% simple interest.

(6) Find the amount to be paid if John borrowed a sum of $5200 at 8% simple interest for 8 years.

(7) Calculate the amount due if Susan borrowed a sum of $3650 at 3% simple interest for 4 years.

(8) Charles had to pay $4251 in order to furnish the loan taken 3 years before. If the rate of simple interest was 3% then find the sum borrowed.

(9) Christopher took a loan of $6000 at the rate of 9% simple interest per annum. If he paid an amount of $11400 to clear the loan, then find the time period of the loan.

(10) What amount does Thomas have to pay after 5 years if he takes a loan of $3800 at 2% simple interest?